Iconic American Infrastructure: The 6th Street Bridge

The Sixth Street Viaduct, also known as the Sixth Street Bridge, is a viaduct bridge that connects the Arts District in Downtown Los Angeles with the Boyle Heights neighborhood.Built in 1932, the viaduct is composed of three independent structures: the reinforced concrete west segment, the central steel arch segment over the river, and the reinforced concrete east segment.It spans the Los Angeles River, the Santa Ana Freeway (US 101), and the Golden State Freeway (I-5), as well as Metrolink and Union Pacific railroad tracks and several local streets.Between 1903 and 1913, the entire building was torn down in phases and replaced by the current Grand Central Terminal.During the construction of the viaduct in the 1930s, an onsite plant was used to supply the concrete for construction.Estimates stated that the viaduct had a 70 percent probability of collapse due to a major earthquake within 50 years.

• Despite its historical status, the bridge was closed for demolition and replacement in January 2016 due to concerns over seismic instability.

• The new bridge, designed by architect Michael Maltzan and the HNTB Design-Build team, is set to be completed in 2019. It is expected that it will take nine months to demolish the existing bridge. City leaders are also looking into building parks and plazas around the newly built bridge.